Device for regulating the advance of an ignition distributor for internal combustion engines



July 20, 1965 R. TAGLIABUE 3,196,224

DEVICE FOR REGULATING THE ADVANCE OF AN IGNITION DISTRIBUTOR FOR INTERNAL COMBUSTION ENGINES Filed Aug. 1, 1962 United States Patent I 3,196,224 DEVICE FOR REGULATIN G THE ADVANCE OF AN IGNITION DISTRIBUTOR FOR INTERNAL COM- BUSTION ENGINES Renzo Tagliabue, Milan, Italy, assignor to Fabhrica Italiana Magneti Marelli S.p.A., Milan, Italy, a corporation of Italy Filed Aug. 1, 1962, Ser. No. 214,094 Claims priority, application Italy, Sept. 28, 1961, 17 ,396/ 61 9 Claims. (Cl. 200-22) The present invention relates to a regulation device for the manual advance of an ignition distributor for internal combustion engines, such device being of the type in which the regulation of the advance is obtained by varying the length of a link connecting the depressor membrane to the contact breaker plate.

In the device of this class, the alteration of said length is made possible in that the connecting link is constituted by two'axially arranged parts connected with each other by means of a coupling joint, the manual rotation whereof causes an approach or a spacing apart of said parts.

The movement in either direction, of the connecting link portion associated with the breaker plate, causes a corresponding angular displacement of said plate with respect to the driving shaft of the distributor, enabling thereby the regulation of the ignition time.

In the conventional devices, as known, the connecting link control system is somewhat complex and cumbersome on account of the number of accessories necessary for coupling the two component parts and to control the distance between them. Further, the various members bring about an increase of the'mass of the connecting link by which they are carried, thereby reducing the sensitiveness of the device to the continuous alternating movements of the depressor membrane.

It is an object of present invention to simplify and lighten the manual control system of the advance regulation by having recourse to a sole coupling member of the connecting link portion in lieu of the coupling joint.

Another object is to provide a system for the amplification of the movement of the connecting link portion connected to the contact breaker plate, so as to facilitate the reading of the displacements, even though they are very small.

According to the present invention both the coupling and the control of the two parts of the connecting link are achieved by means of a sleeve directly engaged with the said two portions by means of threads.

In order to further lighten the movable member, the sleeve may be made of a suitable light material.

The amplification of the movement of the connecting link is obtained by differentiating the threads of the connecting link portions and correspondingly of the portions of the associated sleeve threads.

The invention will now be described in connection with the appended drawing, which shows, by way of example only, an ignition distributor according to the invention, in cross section.

In the figure, 1 is the distributor body; 2 is the contact breaker carrying plate journalled by a bushing 1 secured to the body 2, 3 is the distributor shaft and 4 the cam keyed to the said shaft. The said ca-m acts upon the contact breaker constituted by the small hammer 5 with movable contact and by joint plate 6 with a stationary contact. The joint plate 6 is in series with the primary cable 7, in turn in parallel with the condenser 8.

A support plate 9 rigidly connects the depressor capsule 10 to the distributor body 1. In particular, the capsule is secured to the angular portion 9' of the support. Within the capsule there is anchored the membrane 11 subjected to the engine depression through the fitting 12 and to the action of the return spring 13.

The connecting link which connects the membrane 11 with the contact breaker plate 2 includes the two parts 14 and 15 which are engaged at their threaded ends with the sleeve 16.

The part 14, which is fastened at its end to the membrane 11, has a prismatic portion 14' which extends through a hole of corresponding shape in the bent-over support 9' and in the bottom portion 10 of the capsule. In this relationship the part 14 may move in an axial direction'but is prevented through engagement with the sides of the hole or opening in members 10' and 9 from rotational movement.

The part 15 is anchored to the plate 2 by means of the end eyelet 15.

The sleeve 16 is provided with a reference index I to read the displacement of the sleeve upon a graduated scale G correspondingly reproduced upon the plate 9. Said plate further carries a leaf spring 17 preventing any accidental rotation of the sleeve while still permitting it to move axially.

To that end the sleeve has a suitable enlargement 16' to engage with said leaf spring 17 and which serves at the same time as the control ball grip of the sleeve.

The sleeve is engaged with the connecting link portions 14 and 15 by means of threads 18, 19. The thread 13 formed between the connecting link portion 14 and the corresponding sleeve portion has a larger pitch than the thread 19, realized between the connecting link portion 15 and the corresponding portion of the sleeve.

This dilferent thread pitch enables to achieve an enlarged reading of the displacements of the connecting link portion 15.

Let us suppose that the thread 18 has a pitch of 1 mm. and the thread 19 a pitch of 0.7 mm.

It is to be understood that during the rotation of the sleeve 16 the axial displacement of the sleeve is 1 mm. at each revolution thereof, whereas the displacement of the part 15 is only 0.3 mm.

In fact, during unthreading or threading of the sleeve on the portion 14 through 1 mm. at every revolution, the part 15 takes up the said displacement in the proportion of 0.7 mm. and for the diiference of 0.3 mm. it is forced to move (being pulled or pushed) in the advancement direction of the sleeve.

From the above it will be apparent that with rotational movement of the sleeve in either direction the parts 14 and 15 will move axially in the same direction but that due to the different pitches of the threads, one of these parts will move farther in the axial direction than the other, thus lengthening or shortening the linkage. To permit this operation the threads of parts 14- and 15 must be of opposite lead; that is, if the thread on part 14 is a right hand thread then the thread on part 15 must be a left hand thread, and vice versa.

This system provides a vernier control of the adjustment, and only a slight displacement can be read on scale G.

For the purpose of taking up the backlash of the threads 18419 and for achieving a braking action on the sleeve 2. spring 21 is provided which maintains the component parts of the connecting link under tension.

The said spring is housed at one end thereof in the cavity made in the body of the part 114 and rests at the other end against the end of the part 15.

With the above described device the regulation of the distributor advance is very simple and immediate; in fact, it suffices to manually screw the, sleeve 16 in or out, as the case may be, to give the breaker plate 2 a rotation so as to advance or retard the ignition time. Supposing a clockwise direction of the rotation of the shaft 3, as seen from the contact breaker side, for each extension of the connecting link there is a clockwise rotation of the plate and therefore a late setting of the ignition point. For each shortening of the connecting link there is on the contrary, an anticlockwise rotation and therefore an advance of the spark. The arrows A and R marked upon the support at the graduated scale indicate the direction in which the ignition is advanced or retarded.

The graduation of the scale G allows an easy reading of the setting in degrees of both the advance ignition and the late ignition.

The tuning operations of the device are remarkably simplified in that the micrometric regulation of the ignition point is controlled through an amplified reading.

The control sleeve 16 is of plastic material, to the purpose of lightening the same and to reduce to a minimum the inertia of the movable member connecting the membrane 11 of the depressor to the plate carrying the contact breaker 2. In such a manner the system, owing to its minimum inertia, is very sensitive to the pressure alterations of the engine which stress the membrane for the automatic regulation of the ignition advance.

The leaf spring 17, of a suitable form prevents the possible phase-displacement of the system while still enabling an axial movement of the sleeve under manual control.

The invention has been described and illustrated with reference to a particular embodiment form thereof but it is obvious that modifications or changes can be made in the device without departing from the spirit of the invention or the scope of the appended claims.

Thus, for instance, the pitch of the thread 19 might be greater than that of the thread 18. Of course, in such a case, the rotations are inverted with respect to the illustrated case.

I claim:

1. In an ignition distributor device, a contact breaker carrying plate which is rotatable in one direction to advance the timing and in the other direction to retard the timing, a depressor membrane, a connecting link having two threaded parts one of which is connected to said membrane and the other of which is connected to said plate, said parts having threads of different pitch, and a sleeve in threaded engagement with each of said parts, whereby rotation of said sleeve is effective to change the length of said link and thus rotate said plate to alter the timing of the distributor device.

7 2. In an ignitiondistributor device, a contact breaker carrying plate which is rotatable in one direction to advance the timing and in the other direction to retard the timing, a depressor membrane, a connecting link having two threaded parts one of which is connected to said membrane and the other of which is connected to said plate, a sleeve in threaded engagement with each of said parts whereby rotation of said sleeve is effective to change the length of said link and thus rotate said plate to alter the timing of the distributor device, and means for preventing rotational movement of said sleeve while permitting free axial movement thereof, said means being releasable to permit rotation of said sleeve when a predetermined torque is applied to said sleeve, said means including a leaf spring.

3. In an ignition distributor device, a contact breaker carrying plate which is rotatable in one direction to advance the timing and in the other direction to retard the timing, a depressor membrane, a connecting link having two threaded parts one of which is connected to said membrane and the other of which is connected to said plate, a sleeve in threaded engagement with each of said parts whereby rotation of said sleeve is effective to change the length of said link and thus rotate said plate to alter the timing of the distributor device, and means for engaging the exterior of said sleeve to prevent rotational movement of said sleeve while permitting free axial movement thereof, said means being releasable from said sleeve to permit rotation of said sleeve when a predetermined torque is applied to said sleeve.

4. In an ignition distributor device, a contact breaker carrying plate which is rotatable in one direction to advance the timing and in the other direction to retard the timing, a depressor membrane, a connecting link having two threaded parts one of whichis connected to said membrane and the other of which is connected to said plate, a sleeve in threaded engagement with each of said parts whereby rotation of said sleeve is effective to change the length of said link and thus rotate said plate to alter the timing of the distributor device, said sleeve having an enlarged portion thereon, and a leaf spring engaging said enlarged portion of said sleeve to normally prevent said sleeve from rotation, said spring being resilient whereby it is released from engagement with said portion upon the application of a predetermined torque to said sleeve to permit rotation of said sleeve.

5. In an ignition distributor device, a contact breaker carrying plate which is rotatable in one direction to advance the timing and in the other direction to retard the timing, a depressor membrane, a connecting link having two threaded parts one of which is connected to said membrane and the other of which is connected to said plate, said parts having threads which are in the same direction but of different pitch, and a sleeve in threaded engagement with each of said parts, whereby rotation of said sleeve is effective to change the length of said link and thus rotate said plate to alter the timing of the distributor device.

6. A device as set forth in claim 5 including a scale located adjacent said sleeve and graduated to indicate the longitudinal movement of said sleeve.

7. A device as set forth in claim 5 including spring means within said sleeve and engaging the ends of said parts for urging said parts longitudinally of said sleeve to bring the threads of said part into close engagement with said sleeve.

8. In an ignition distributor device, a contact breaker carrying plate which is rotatable in one direction to advance the timing and in the other direction to retard the timing, a depressor membrane, a connecting link having two threaded parts one of which is engaged at its one end with said membrane, and the other of which is pivotally engaged at its one end with said plate, the other ends of said parts having threads of difierent pitch, and a sleeve in threaded engagement with said other ends of each of said parts, whereby rotation of said sleeve is effective to change the length of said link and thus rotate said plate to alter the timing of the distributor device, said two 5 6 to said plate, the other ends of said parts being threaded References Qited by the Examiner With one part having a right hand thread and the other UNITED STATES PATENTS part a left hand thread, the pitch of said threads on one of said parts being different from the threads on the other 2278320 3/42 Kath 287 60 of said parts, and a sleeve in threaded engagement with 5 2546781 7/53 Doyen 200 31 each of said parts whereby rotation of said sleeve moves 3036166 5/62 Cofiin 20O 31 both of said parts in the same axial direction with re- FOREIGN PATENTS spect to said sleeve and changes the length of said link in 609,549 10/48 Great Britain relation to the diiference in the pitches of said threads to 371,920 6/39 Italy thus rotate said plate and alter the timing of the dis- 10 tributor device. BERNARD A. GILHEANY, Primary Examiner. 

1. IN AN IGNITION DISTRIBUTOR DEVICE, A CONTACT BREAKER CARRYING PLATE WHICH IS ROTATABLE IN ONE DIRECTION TO ADVANCE THE TIMING AND IN THE OTHER DIRECTION TO RETARD THE TIMING, A DEPRESSOR MEMBRANE, A CONNECTING LINK HAVING TWO THREADED PARTS ONE OF WHICH IS CONNECTED TO SAID MEMBRANE AND THE OTHER WHICH IS CONNECTED TO SAID PLATE, SAID PARTS HAVING THREADS OF DIFFERENT PITCH, AND A SLEEVE IN THREADED ENGAGEMENT WITH EACH OF SAID PARTS, WHEREBY ROTATION OF SAID SLEEVE IS EFFECTIVE TO CHANGE THE LENGTH OF SAID LINK AND THUS ROTATE SAID PLATE TO ALTER THE TIMING OF THE DISTRIBUTOR DEVICE. 